A method and apparatus for detecting a high flying condition of a transducer head in a computer disk drive is provided. The method and apparatus allow the detection of high fly write events that occur over one or a small number of data sectors. In addition, the present invention provides a method and apparatus for detecting high fly write events with a great deal of sensitivity. The method and apparatus of the present invention provide quick response and high sensitivity by monitoring the strength of a signal derived from data written to the disk, and signaling a high fly write event if the monitored signal strength in connection with a particular piece of data is less than a stored high fly write number corresponding to that piece of data by a predetermined amount.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for detecting a high flying condition in a disk drive, comprising: providing a disk surface having a track, said track including a plurality of AGC fields each corresponding with at least one data sector in said track; measuring an amplitude associated with each of said plurality of AGC fields, said amplitudes corresponding to flying heights of a transducer head over the disk surface at locations corresponding to said plurality of AGC fields; storing values corresponding with said measured amplitudes onto said disk surface; prior to writing data to a data sector in said track, measuring an amplitude associated with the AGC field that corresponds with said data sector and comparing said measured amplitude to a stored value corresponding to the AGC field; and generating a signal indicating a high flying condition if said comparison is unfavorable.
2. The method of claim 1 , wherein said stored value comprises a reference value.
3. The method of claim 2 , wherein said reference value is derived from information stored on said disk.
4. The method of claim 1 , wherein said stored value comprises a reference value plus a marginal value.
5. The method of claim 1 , wherein said stored value is stored on said disk surface in a servo sector associated with the AGC field.
6. The method of claim 1 , wherein said stored value is stored on said disk surface in a servo in data sector associated with the AGC field.
7. The method of claim 1 , wherein said stored value is stored on said disk surface in a data sector associated with the AGC field.
8. The method of claim 1 , wherein said comparison is unfavorable if said measured value is less than said stored value.
9. The method of claim 1 , wherein said stored value encodes a numerical value.
10. The disk drive of claim 1 , wherein a plurality of amplitudes associated with each of said plurality of AGC fields are measured and said stored values corresponding with said measured amplitudes represent an average value associated with each of the plurality of AGC fields.
11. The disk drive of claim 1 , wherein amplitudes are measured for all of the AGC fields in said track.
12. The disk drive of claim 1 , wherein amplitudes are measured for all of the AGC fields on the disk surface.
13. A method for detecting whether a flying height of a transducer head over a disk surface in a disk drive exceeds a desired amount, said disk surface having a track, said track including a plurality of AGC fields each corresponding with at least one data sector in said track, said method comprising the steps of: determining standard transducer head flying height numbers, wherein said standard transducer head flying height numbers are based on measured amplitudes associated with each of said plurality of AGC fields; storing said standard transducer head flying height numbers on said disk surface; prior to writing data to a data sector in said track, determining an amplitude associated with the AGC field associated with said data sector to obtain an observed transducer head flying height number; comparing said selected standard transducer head flying height number associated with said AGC field to said observed transducer head flying height number; and signaling a high fly write condition if said comparison indicates a high fly write event.
14. The method of claim 13 , wherein said step of determining standard transducer head flying height numbers comprises setting said measured amplitudes equal to said standard transducer head flying height numbers.
15. The method of claim 13 , wherein said step of determining standard transducer head flying height numbers comprises: adding a marginal value to said measured amplitudes to obtain said standard transducer head flying height numbers.
16. The method of claim 13 , wherein said step of storing said transducer head flying height numbers to said disk surface comprises storing said numbers in servo sectors of said disk surface.
17. The method of claim 13 , wherein said step of storing said transducer head flying height numbers to said disk surface comprises storing said numbers in data sectors of said disk surface.
18. The method of claim 17 , wherein said data sectors are located in customer data regions of said disk surface.
19. The method of claim 13 , wherein said step of determining standard transducer head flying height numbers is performed prior to delivery of said disk drive to an end user.
20. The method of claim 13 , wherein said step of determining standard transducer head flying height numbers is performed prior to storing customer data on said disk.
21. The method of claim 13 , wherein said step of comparing comprises subtracting said observed transducer head flying height number from said standard transducer head flying height number.
22. The method of claim 13 , wherein a high fly write event is indicated if said step of comparing results in a number that is positive.
23. A method for detecting a high flying condition in a disk drive, comprising: providing a disk surface having a track, said track including a plurality of groups of servo bursts each corresponding with at least one data sector in said track; measuring an amplitude associated with each of said plurality of groups of servo bursts, said amplitudes corresponding to flying heights of a transducer head over the disk surface at locations corresponding to said plurality of groups of servo bursts; storing values corresponding with said measured amplitudes onto said disk surface; and prior to writing data to a data sector in said track, measuring an amplitude associated with the group of servo bursts that correspond with said data sector and comparing said measured amplitude to a stored value corresponding to the group of servo bursts.
24. A method for detecting a high flying condition in a disk drive, comprising: providing a disk surface having a track, said track including a plurality of ERC fields each corresponding with at least one data sector in said track; measuring an amplitude associated with each of said plurality of ERC fields, said amplitudes corresponding to flying heights of a transducer head over the disk surface at locations corresponding to said plurality of ERC fields; storing values corresponding with said measured amplitudes onto said disk surface; and prior to writing data to a data sector in said track, measuring an amplitude associated with the ERC field that corresponds with said data sector and comparing said measured amplitude to a stored value corresponding to the ERC field.
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July 13, 2001
January 17, 2006
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